In a conventional switching hub, when the status of either a first port or a second port changes from link-up to link-down, in spite of no communication between the first port and the second port, the other port is still link-up, thereby consuming wasted power. As a technique for solving the above problem, a technique is known which stops the operation of a clock control circuit so as not to generate a clock signal when no data received from a network device is present during a period of no communication due to, for example, a link-down, as disclosed in, for example, JP2007-328671 A. However, such a technique requires clock control for each port, and accordingly the configuration of and the processing flow in the switching hub device may become complex.